Hydrocarbon fluids, such as oil or natural gas, are recovered from subsurface formations through wells drilled into the formations from the surface. A substantial amount of the hydrocarbon fluids may remain trapped in the formations if produced only using primary depletion (natural pressure depletion). When natural pressure is insufficient to adequately produce the trapped fluids, secondary recovery operations may be employed. In such operations, a fluid, known as a flooding liquid, is forced into the formation through an injection well. As the flooding liquid moves into the formation, the hydrocarbons are displaced and produced through production wells. Various fluids, such as water, air, carbon dioxide, etc. may be used as flooding fluids. When applied subsea, secondary recovery operations often employ seawater as the flooding liquid.
A flooding liquid is injected into formations under relatively high pressure. The characteristics of the formations determine the injection pressure. In general, the injection pressure should be high enough to displace the trapped hydrocarbons, and low enough to prevent fracturing of the formations. Consequently, the pressure of the flooding liquid should be carefully monitored.